Control system



P. M. STIVENDER 1,844,719

CONTROL SYSTEM Feb. 9, 1932.

Filed Nov. 22, 1923 Patented Feb. 9, 1932 N D STATES PATENT' OFFICE:

PAUL H. STIV'ENDER, OF WEST ALLIS, WISCONSIN, ASSIGNOR TO ALLIS-CHALIEBS MANUFACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF QELAWABE coNTRoL SYSTEM Application filed November 22, 1929. seriainaeoaon.

This invention relates to electrical control syst ms, and more particularly to systems A whic respond to or control the relative frequencies of sources of alternating current For the sake of brevity the words' alternating current will be hereinafter abbreviated I to a=c.

.ject is the provision of means whereby the frequencies of the two sources are brought to the same value in response to said means.

A further object is the provision of means,

respondingto the relative frequencies of two a=c. sources which comprises relays as its essential elements. A more specific object is the provision of means whereby the relays are causedto be effectively operated .in different predetermined orders depending upon the relative frequencies of the two sources.

This invention is an improvement on that disclosed in applicants copending application Serial No. 409,072, filed Nov. 22, 1929,

" and a 'furt her object is the simplification of and showing one embodiment of the inven tion, and all these novel features are intended to be pointed out in the claims.

In the drawings:

Fig. l is a diagrammatic view of one embodiment of the invention as it may be applied in the control of a polyphase generator.

Figs. 2 and 3 are across-the-line diagrams i of the same circuits as illustrated in Fig. 1.

Figs. 4 and 5 are vector diagrams illustrating electromotive forces which are applied to certain parts of the system and Fig. 6 is a diagramillustrating various vector polygons resulting from a combination of certain vectors in Figs. 4 and 5.

Referring to Fig. 1 of the drawings theie is here shown a prime mover 4, indicated as a hydraulic turbine. It is to be understood however that the invention is not limited in L its application to anyparticular form of prime mover. The turbine 4 drives a generator 5 supplying the three phase conductors 6 which may be connected by means of a switch 7 to a three-phase line 8. The switch 7 is here shown as provided with an operating coil 9' which may be energized by means of any suitable form of automatic synchronizert Inasmuch as the synchronizer forms no part of the present inventionit has merely been indicated in the drawings.

The turbine 4 is .shown as controlled by means of a gate 11 in the conduit supplying operating fluid thereto. It isof course to be understood that any of the usual means for controlling the supply of operating fluid to a prime mover may be employed. The gate -11 may be operated b means ofa servomotor 12 which is in icated-as controlled by a regulating valve-13. The re ating valve 13 is here shown as controlle in the usual manner by means of a floating lever to the floating pivot of which is connected a centrifugal speed responsive device .contained in the casing 15. The other end of the floating lever 14 is pivotally connected to a nut 16 which is in operative relation to a screw, 18. The'lower end of the screw 18 is suitably connected to the usual dash pot or compensating device 17 the other element of which is operated in unison with the motion of the gate 11. These parts have been shown in diagrammatic form as they are well known in the art and their specific embodiment forms no part of the invention. The screw 18 may be rotated b means of a motor 19 here shown as of the direct current split field type, the field windings being indicated as 20 and 21. One terminal of the armature of motor 19 is connected to abus 22 the other terminal bein connected to a comare connectible to another bus 23, so that if field winding 20 is connected to bus 23 the motor 19 will rotate in one direction whereas are connected to conductors 1 and 2 An other pair of the phase conductors leading\ from the generator has connected thereto a V transformer the secondary terminals of. which are connected to the conductor'2 and a conductor 3.. The conductor 1' is connected by means of a conductor to the conductor 1... The conductors 2,, 2c and 3 are extended to control relays as will ap- Egar hereinafter, and these conductors may controlled by. a switch 26 in anysuitable fashion. v

A relay .27 has one terminal connected to conductor 2' and the other connected, through a resistance 28, to conductor 2,. A rel'ay 29 has one terminal connected to the conductor 2'., there being a resistance 36 interposed as here shown, and the other ter-. minal, through a resistance 30, to'the conductor 3,. A set-up relay 31 is here shown as having one terminal connected to the conductor 1 and the other, through a resistance 32,- to the conductor 2.. An adjustable time limit relay 33 is here shown as connectible across the conductors-1 2 through a resistance 34.

Referring again to relay 27, this is here shown as provided with four contacts all of which are front contacts: B'yfront contacts is meant contacts which are adapted to close a circuit when the relay is energized. In the 33 and two possible shunt or lockout circui 'across-the-line diagrams of Figs. 2 and 3 front contacts are indicated by a air of sarallel lines. The rela coils in t e saidv iagrams are indicated y circles, and the coil and contactsof a 'ven relay bear the same/reference numeral. One of the contacts of relay 27 controls the circuit of motor 19;. another is in a holding circuit for relay 27; another is in, a shunt orlockout circuit for relay 29 and another controls relag;

for relay 31.

Relay 29 is here shown asprovided with four contacts two of which are front contacts nd two back contacts. By back contactsis meant'contacts which are adapted to open a circuit when relay is ener zed. In the across-the -line diagramsof igs. 2 and 3 back contacts are indicated by a pair of (parallcl lines crossed by a'diagonal line.

ne of the front contacts of relay 29 and one of the back contacts thereof are in circuits for the field windings 21 and 20 respectively. An-' other front contact of said relay is in the I holding circuit'for relay 29. The other back contact ofrela 29 is in a shunt or lockout circuit for sai relay.

Relay 31 is here sho wn f as provided with four ontacts three ofwhich are front and one back contact. One-mi the front contacts controls a circuit for motor 19; another front contact controls -th'e circuit fonrelay 33; and another front contact is in the holding circuit for relay 27. The back contact of relay 31 is in one of the lockout circuits for said relay. p

In orderto determine the electromotive orces (hereinafter abbreviated to emfs.)

applied to relays 2.7 and 29 respectively under various conditions, the .vector componentsv of these emfs. will be considered first. Referring now to Fig. 4, the vectors ()2' and Q1 indicate the emfs. betweerra neutral point 0 and the conductors 2'. and 1 respectively. The phase-to-phas'e emf. is then that indicated by the vector marked with the legend.

2 to 1. Referringnow to Fig. 5 and assuming that the polyphase emfs. of the generator and line are in phase, the vectors 0-1, 0-2, and 0'3 correspond to the emfs. between a neutral point 0 and the conductors 1 2.,

and 3 respectively. Sincethe 'circuit for relay 27 vfor example'is as here shown from 2 to 1 to 1 to 2, the emf. across 1 and 2 is 'laid off inthe reverse direction in the diagram in Fig. 5 and bears the legend, 1 i

to 2. The emf.acr0ss the conductors 1 and 3 is laid 01f as the vector bearing legend, 1 to 3, in Fig. 5. In order to determine the emfs. across the relays 27 and 29-the vectors obtained as hereinbefore stated have been laid'ofi' in a diagram of vector polygons in Fig. 6. I

For the the vector polygons the head of the'arrow CO, representing the vector 2 to 1', is at the point 0 in Fig. 6, for various positions of that vector, while the tail of the arrow OA, representing the vector 1 to 2 is at the point 0. It may be'noted that ,-for the .sake of clearnes's, the vectors CO and 0A are shown as side-by-side. though they are actually superimposed when, as assumed, the generator and line arein phase.

It will be apparent from what has been previously stated that the emf. across relay 27 isrepresented by the distance between thep'oints C and A which, when the line and generator are in. phase, is equal to zero. Moreover, since the circuit for relay 29 is from2' to 1'. to 1. to 3 the emf. across this relay is represented by the vector CB. Let

it be assumed that this vector represents a.

v I sake of convenience 1n forming potential difference of 100 volts and that the resistance 30 is so'adjusted that for 100 volts across the conductors 2' and 3,, the relay 29 will not be effectively energized. Let 1t further be assumed that in'case the emf. across these conductors rises to 130 volts; that said relay will be effectively energized. The re 'by' way of example and it will be apparent that other values may be utilized.

In case the line and generator frequencies .are not equal the vectors 1, 2., 3', and 1, 2, 3

will rotate at different speeds. In order to consider the effectof the relative rotation as between these vectors we may consider the vectors 1, 2, 3 as stationary and the vectors 1', 2', 3 as revolving with'respect thereto.

In connection with Fig. 6 this will mean that we-will consider the vectors OA and OB as stationary and the vector CO. as revolving about the point 0 in either one direction or the other depending upon whether the line frequency is above or below that of the generator.

If it be assumed that when the line fre-- quency is below that of the generator, thevector CO rotates in a counter-clockwise direction, then when the'outside end of said vector reaches the position C therelay 29 will be effectively energized since the voltage across this relay is now represented by vector CB, in the assumedinstance, 130 volts. .The energization of relay 29 closes the front contact of said relay in the circuit'for field winding 21 and openstheback contact thereof in the circuit of field winding 20, but since relay 27 is deenergized, the motor circuit remains deenergized.. lVhen the vector CO reaches the position C the relay 27 will be energized, the emf. across this relay being then represented by vector C A which in the'instance assumed is 130 volts. Itmay be noted that .vector C B and there r through a front,

relay in, said relay the emf. across relay 29. is represented by ore this relay remains energized. The "energization causes a front contact of that relay to complete a circuit for motor 19 through field winding 21 and through front contacts of relays 29 and 31.. Another-front contact of re-- lay 27 completes acircuit for relay 33 contact of relay 31. -Anbeing then fed from conductors 1 and 2' through front. contacts of relays 29 and 27 and resistance 36. The remalnmg front contact of relay 27 locks said being then fed from conductors 2' and 1 through front contacts of relays 31 and 27. The motor 19 now rotates 'in such direction as to move the nut 16 in the proper direction for adjusting the gover- Q of relay 27' nor to lower the speed of the generator 5.

Meanwhile, as stated above, the adjustable time limit relay33'has been energized and after a predetermined time this relay closes its contact thereby shorting relay 31 through locked out as long as relay 27 remains energized, and this depends upon the position of the rotating vector CO. 'As soon as this vector reaches any position such that the emf. across relay 27 is 100 volts or less (in theillustrative example) relay 27 will drop out opening the lockout circuit for relay 31 and the relay 31 will be energized, and the cycle of operations hereinbefore described may be repeated. This cycle of operations will be repeated the oftener the greater the difference in frequency between the generator and the line. Qn the other hand, if the difference is slight the cycle-will be repeated at comparatively long intervals since the rotation of vector CO is then very slow.

Let it now be assumed that the frequency which case the vector CO will rotate in a direction opposite from that previously assumed, that is, in a clockwise direction@ If we begin again with the emfs. of line and generator in phase, both relays 27 and 29 are deenergized. 'hen the vector CO reaches the point C the emf. G A is sufficient to energize relay 27. Since that-back contact of relay 29 which is in the circuit of the'field winding 20 is closedat the time relay 27 is energized, a circuit is completed for motor 19 through 'field winding 20 and front contacts of relays 27 and 31. The energization of relay 27 also completes a holding circuit for said relay as hereinbefore described. Also. a front contact of relay 27 completes a lockout circuit for relay 29 through a back contact of relay 29; Another front contact of relay 2; energizes the adjustable time limit relay as hereinbefore described causes the motor 19 to run in such direction'th'at the frequency of the generator is caused to increase.

Meanwhile, the time limit relay .33 is moving its contact toward closed position and when the same closes, the relay 31 is locked out until relay 27' is deenergized, as previous'ly described. Deenergization of relay 27 opens the loclmut circuit for relay 29, and permits relay 31 to be reenergized. The cycle hereinbefore described may then be repeated.

It willbe evident that when there is a large difference in frequencies between the generator and line the'speed and frequency of the generator will be changed rapidly to cause it to approach that of the line and as the difference infrequencies becomes less the rapid- (whether it was at first higherv or lower in frequency) the switch 7 may be closed when the generator and line are in phase and this may be accomplished in any suitable manner,

I if desired, by anautomatic synchronizer l0 2 here indicated merely by an appropriate legend. j

While the connections of the transformers for feeding relays 27 and 29 are preferred as shown, it will be apparent to those skilled in 2 the art that the vector polygons as described in connection with Fig. 6 will apply equally well if the connections 1' and 2' are reversed, that is, the conductor 2., leading to the upper (as viewed in Fig. 1) terminals of relays 27 3 and 29 becomes 1' and the conductor is connected to terminal 2' instead of 1 The only difference is that'thecondition representedby thevectors in full lines in Fig. 6

then represents the condition whenthe genera'torand line are 180 degrees out of phase.

The principleof operation of the relays as hereinbefore described however remains unchanged as far as the control of the speed of the generator to bring the frequency to the 40 same as that of the line is concerned.

,It should be understood that it is not de- "sired ,to limit the invention to the exact details of description shown and described, for obvious modifications may occur to persons 4.5 skilled in the. art.

It is claimed anddesiredto secure by Letters Patent: I

. 1. In combination, a pair of polyphase a=c. sources, a'pair of relays, meansfor so connecting said r'elays'to said sources that from *a predetermined phase relation of'said sources said relays are energized in predetermined sequences dependent upon the relative frequencies of saidsources, an electrical de; vice, and means whereby energ zationof one of said relays at a time while the other ofsaid relays is energized produces a predetermined effect on said device and energlzation of said one of-sa-id relays at a time while the other of 80 said relays is deenergized'producesa difi erent predetermined effect on said device.

2. In combination, a pair' of polyphase a=c. sources, a pair of relays,means "for so connecting said relays to said sources that from a. predetermined. phase relation of said The'speed at which'motor 19v operates may sources said relays are energized in a predetermined sequence at a time when the frequency of one of said sources is higher than the frequency of the other of said sources, and

means whereby 'the' energization of the last one of said sequentially energized relays at said time locks both of said relays in their respective energized: positions .for a definite time. r

' 3. In. combination, a pair of polyphase a=c. sources, a pair of relays, means for so connecting said relays to 'said'sources that from a predetermined phase relation of said sources said relays are energized in a predetermined order at a time when the frequency of one of said sources is lower than the frequency of the otherof said sources, an electrical device; means whereby energization of one of said relays at said time while the other of said relays is deenergized causes a predetermined efi'ect on said device, and means wherebyenergization of said one of said relays at said time locks said relay in and locks theother of said relays out fora definite time.

I, 4. In combination, a pair of a=c. sources, a pair of relays, means for so connecting sald relays to sa d sources that from a predetermined phase relationof said sources said relays areenergized in a predetermined order at a time when the frequency of one of said sources is higher than the frequency of the other of said sources, an electrical device,

means whereby energization of one of said relays at said time while the other of said relays is deenergized causes a predetermined effect on said devlce, means w locks said relay in and locks the other relay out, and means for rendering said locking means inoperative after a predetermined time.

5. In combination,a polyphase a= c. line, a polyphase a=c. generator, a prime mover for driving said generator, a pair of relays,

means for so connecting said relays to said line and generator that from a predetermined phase relation of said line and generator said ereby energization of said one of said relays at said time.

relays are energizedin a predetermined order dependent upon the relative frequencies of said line and generator, means including a pair of control circuits for raising and low ering the speed ofsaid prime mover respectively, one of said relays having back and front contacts in said circuits respectively, a common connection for carrying current through both of said circuits, the other of said relays having a front contact in said connection; I

6. In combination, a polyphase a=c. line,

a polyphase a=c. generator, a prime mover for drivingsaid generator, a pair of relays,

means for so connecting said relays to said line and generator that frcina predetermined phase relation of said lineand generator said relays are energized in a predetermined order front I lay havinga 5 1y, one of said relays having back and front contacts in said circuits respectively, a common connection for carrying current through both of said circuits, the other of said relays having a front contact in said connection, a normally energized set-up relay having a contact in'said connection, and means for deenergizing said set-up relaya predetermined time after said other of said pair of relays is energized.

1 7. In combination, a polyphase a=c. line, a polyphase a=c. generator, a prime mover for driving said generator, a pair of relays, means for so connectin said relays to said line and generator that f -om a predetermined phase relation of said line and generator said relays are energizedhn a predetermined'order dependent upon the relative frequencies of said line and generator, means including a pair of control circuits for raising and lowering the sped of said prime mover respective, ly, one of said relays having back and front contacts in said circuits respectively, a common connection for carrying current through both of said circuits, the other of said relays having a front contact. in said connection, a

. a normally energized set-up relay having a contact in said connection, means for deenergizing ,said set-up relay a predetermined time after said-other of said pair of relays is ener- 5 gized, and means for reenergizing said set-up relay when said last named relay is again deenergi zed. v

8'. In combination, a. polyphase a=c. line, a polyphase a=c. generator, a prime mover for driving said generator, a pair. of relays,

, means for so connecting said line and generator'that from a predetermined phase relation of said line and generator said relays are energized in a predetermined order relays to said.

dependent upon the relative frequencies of and line an generator, means including a pair-of control circuits for raising and lowering the speed of said prime mover respectively, one of said relays having back and contacts in said circuits respectively, a 7 common connection for carrying current through both of said circuits, the other of said relays having a front contact in said L connection, a normally-energized set-up gecontact in said connection,,means v for deenergizing said set-up relay a redeterv mined time after said other of sai pair of relays is energized, and means whereby der energi'zation of said set-up relay locks the same out until predetermined conditions obtain.

9. In combination, a polyphase a c line, a polyphase a==c. generator, a prime mover for dr ving said generator, a pair of relays L means for so connecting said 'relaysto sai respectively, one of said relays having back and means including a contact of said setline and generator that from a predetermined phase. relationv of said line and generator said relays are energized in a predetermined order dependent upon therelative frequencies of said line and generator, means including a pair of control circuits for raising and lowerin the speed of said prime mover respective y, one of said relays having back and front contacts in said circuits respectively, a common connection for carrying current through both of said circuits,

the other of said relays having a front contact in said connection, and means whereby energization of said other of said relays locks the said one of said relays in or out depending upon whether said other of said relays" is energized or deenergized. 1

10. In combination, a polyphase a=c. line, a polyphase a=c. generator, a prime mover for driving said generator, a pair of relays, means; for so connecting said relays to said line and generator that from a predetermined phase relation of said line and genera tor'said relays are energized in a predetermined order dependent upon the relative frequencies of said line and generator, means ineluding a pair of control circuits for raising and lowering the speed of said prime mover and front contacts in said circuits respectively, a common connectionfor' carrying current through both of said circuits,- the other of said relays having a front contact in said connection, a normally energized setup relay having a contact in said connection,

up relay whereby energization of said other of said relays locks said one of said relays in or out depending upon vvhether said other of said relays is energized or deenergized. 11. In combination, a polyphase a=c. line, a polyphase a=c. generator, a prime mover for driving said generator, a pair of relays, means for so connecting said relays to\ said line and generator that from a predetermined phase relation of said line and generator said relays are energized in a predetermined order dependent upon the relative frequencies of said line and generator, means including a-pair of control circuits for raisingand lowering the speed of said prime mover respectively, one of said relays having back and front contacts in said circuits respectively, a common connection for carrying current through both of said circuits, the other of said relays having a front contact in said connection, a normally energized set-up relay having a contact in said connection, means including a contact of said set-up relay whereby energization of said other of said relays locks said one of said ,relays-in or out depending upon whether set-up relay atprede'termined time after said other of said relays is-energized.

12. In combination, a polyphase a=c. line, a polyphase a=c. generator, a prime mover for driving said generator, a pair ofrelays,

- means for so connecting said relays to said lineand generator that from a predetermined phase relation of saidline and generator said relays are energized in a predetermined order dependent upon the relative frequencies of said line and generator, means including a pair of control circuits for raising and loweringthe speed of said prime mover respectively, one of said' relays having back and front contacts in said circuit-s respectively, a common connection for carrying current through both of said circuits, the other of said relays having a" front contact in said connection, a normally energized set-uprelay' 13. In combination, a plurality of inde pendent alternating current sources, a circuit supplied w1th a smgle phase emf. from one of said alternating'current sources, a circuit supplied withpolyphase emfafrom another of said alternating current sources, a pair of relays, means for causing one of said relays to be intermittently actuated in response to variations in the vector sum of said single phase emf. and the emf. of one phase of said polyphase emfs. when the, frequencies of said alternating current sources are unequal,

means for causing the other of said relays to he intermittently actuated" in response to variations in the vector sum of said single phase, emf. and the emf; of another phase of said polyphase emfs. when the frequencies of said sources are unequal, means actuated by the actuation of one of saidrelays for locking both of said relays in their respeccausing the other of said relays to be intermittently actuated in response to variations inthevectorsumofsaid single phase emf and the emf. of another phase of. said polyphase emfs. when the frequencies of said sources are unequal whereby said, relays are actuated in predetermined sequences dependent upon the 7 relative frequencies of said sources, a reversible translating device, and means for causing said translating device to operate in one direction in response to the actuation of both of said relays and for causing said translating device to operate in the reverse direction in response to the actuation of a certain one only of said relays.

In testimony whereof, the signature of the inventor is alfixed hereto.

' PAUL M. STIVENDER.

'tive positions, and means for rendering said locking means lnoperatlve after a predeterminedtime. 1

14: In combination, a plurality of independent alternating current sources, a' circuit supplied with a single phase emf. from one of said sources, a circuit supplied with polyphase emfs. from another of said alternating current sources, a' pair of relays,

means for causing one ofsaid relays to be l intermittently actuated in response to variatlOIiSlll the vector sum of said single phase emf; and the emf. of one phase of said poly- 65 phase emfs.whenthe frequenciesof said alter- M natmg current sources are unequal, means for rec 

